The Proposed research will investigate the following projects: l) Sleep-waking patterns in the isolated forebrain: effects of basal forebrain lesions. 2) The temporal characteristics of behavioral and physiological parameters at sleep onset using a standardized paradigm. 3) Unit recording experiments in the VPL nucleus of the thalamus during physiological sleep and sleep induced by basal forebrain electrical stimulation. 4) Unit recording studies in the VPL nucleus of the thalamus in chronic cerveau isole preparations. 5) The influence of basal forebrain stimulation on autonomic reflexes within the orbit. Our general objectives are to determine the relative contributions of brain-stem and forebrain systems in the neural mediation of the onset of s slow-wave sleep.